It has been known for many years that improved healing rates can be achieved by applying r.f. electromagnetic fields to wounded tissue. The therapeutic effects were considered to be due to heating of the tissue by the field and prior therapy apparatus has been configured to produce r.f. energy levels for tissue heating either on the surface or deep into the tissue. This heating technique is known as diathermy. It is known to pulse the field produced by diathermy apparatus. A specific example of the heating effects achieved with a pulsed field diathermy apparatus is given in "A Trial Involving the Use of Pulsed Electromagnetic Therapy on Children Undergoing Orchidopexy" R. H. C. Bentall and H. B. Eckstein, Zeitschrift fur Kinderchirurgie und Grenzgebiete p 380-398 November 1975.
Heretofore the pulsed electromagnetic field has been produced by hospital or laboratory based equipment comprising an electrical signal generator which feeds an induction coil mounted on a stand, positioned adjacent an area of a patient to be treated. This apparatus is bulky and has the disadvantage that a patient cannot be treated on a continuous intensive basis without being hospitalised.
More recently, it has been appreciated that the therapy produced by an applied r.f. field is not characterised solely in terms of the tissue heating effect of the field. A discussion of this subject is given in my paper entitled "Healing by Electromagnetism-Fact or Fiction" New Scientist Apr. 22, 1976.
I have devised a lower powered portable apparatus for producing the electromagnetic field, suitable for being attached to a patient, to produce therapy at power levels which do not produce any significant tissue heating. Such portable apparatus is described in my U.S. Pat. No. 4,429,698 entitled "Treatment Inductors" and corresponding published U.K. Patent Application No. 2027594.
This portable apparatus comprises a battery driven r.f. oscillator and an antenna which is flexible to overlie an area of tissue to be treated. The apparatus thus can be attached to the patient and left running on a substantially continuous basis. The portable apparatus produces an electromagnetic field typically in the frequency range 3-30 MHz, the particular r.f. frequency not being of great significance as to the efficacy of the therapy. The r.f. field is pulsed in a manner to maximise the therapeutic effect. The field is of a strength which does not produce any significant tissue heating. The portable device thus operates at much lower power levels than bulky diathermy apparatus, typically to produce r.f. field of less than 100 mW cm.sup.-2 as measured at the skin of the tissue, and utilising a fundamentally different premise as to the manner in which a r.f. field may be utilised to effect treatment, namely that the field does not have to produce tissue heating in order to produce an improved healing rate.